Plasma actuator for vehicle aerodynamic drag reduction

ABSTRACT

A plasma actuator includes a first electrode disposed on a substrate, covered by a dielectric layer, and a second electrode disposed on the dielectric layer. In operation, the plasma actuator creates a plasma region, altering air flowing over the actuator. The plasma actuator in various embodiments: has no moving parts, helps to improve fuel economy by reducing aerodynamic drag, improves vehicle stability control under severe unsteady flow environments, reduces wind noise around a vehicle on which the actuator is used, and reduces emission and CO2 foot print through the fuel economy improvement.

FIELD OF THE PRESENT TECHNOLOGY

The present technology relates generally to transportation vehicles suchas automobiles and, more specifically, to aerodynamic drag reduction forautomobiles.

BACKGROUND OF THE PRESENT TECHNOLOGY

Fuel economy is one of the selling points for today's automobile market.Consumers want cars with improved fuel efficiency, so they can realizesavings during their ownership of an automobile.

Fuel efficiency depends on several factors, such as engine design, bodydesign, fuel quality, driving habits, etc. During the process ofdesigning the body, or exterior shape of a car, many factors areconsidered, such as comfort, style, and utility. The exterior shapeimpacts how the car looks, and has a big effect on the aerodynamic drageffect, which affects fuel efficiency of the automobile.

The drag can be reduced by delaying or eliminating the flow separationson the automobile surface or controlling the flow separation at the rearend of automobiles. Such flow controls on the automobile surface requireadditional mechanical equipment to be installed in addition tomodifications to the automobile body. The drag can also be reduced bymodifying the exterior shape. However, the exterior shape cannot bechanged substantially because it impacts the aesthetics of the car,which of course affects the desirability of the car by consumers.

The present technology is directed primarily to a system that reducesthe drag and improves the fuel efficiency of automobiles withoutsacrificing aesthetics.

SUMMARY OF EMBODIMENTS OF THE TECHNOLOGY

The present technology includes a plasma actuator that, when activated,creates a plasma region, altering the flow of fluid around the plasmaactuator. In one embodiment, the plasma actuator comprises a substrate,a first electrode disposed on the substrate, a dielectric layer disposedon the substrate and covering the first electrode, and a secondelectrode disposed on the dielectric layer.

In an alternative embodiment, the present disclosure describes anautomobile having at least one plasma actuator disposed on or at anexterior surface of the automobile, wherein the plasma actuatorcomprises a substrate, a first electrode disposed on the substrate, adielectric layer disposed on the substrate and covering the firstelectrode, and a second electrode disposed on the dielectric layer.

In another alternative embodiment, the present disclosure describes aplasma actuator comprising a substrate, a first electrode disposed onthe substrate, a second electrode disposed on the substrate and separatefrom the first electrode, a first dielectric layer disposed on thesubstrate and covering the first electrode, a second dielectric layerdisposed on the substrate and covering the second electrode, a thirdelectrode disposed on the first dielectric layer, and a fourth electrodedisposed on the second dielectric layer.

Further features and advantages of the technology, as well as thestructure and operation of various embodiments of the technology, aredescribed in detail below with reference to the accompanying drawings.It is noted that the technology is not limited to the specificembodiments described herein. Such embodiments are presented herein forillustrative purposes only. Additional embodiments will be apparent topersons skilled in the relevant art(s) based on the teachings containedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate the present technology and, togetherwith the description, further serve to explain the principles of thetechnology and to enable a person skilled in the relevant art(s) to makeand use the technology.

FIG. 1 is a schematic diagram of a cross section view of a plasmaactuator according to the present technology.

FIG. 2 is a perspective view of the schematic diagram of the plasmaactuator of the present technology.

FIG. 3 is an alternative schematic diagram of a cross section view ofthe plasma actuator of the present technology.

FIG. 4 is an illustration of an automobile equipped with plasmaactuators of the present technology.

FIG. 5 is another illustration showing placement of plasma actuatorsunder the body of an automobile.

FIG. 6 is a third illustration showing placement of plasma actuators onan automobile.

FIG. 7 is a fourth illustration showing placement of plasma actuators ona side view mirror.

FIG. 8 illustrates use of a plasma actuator for boundary layer flowcontrol.

FIG. 9 illustration an application of a plasma actuator.

FIG. 10 depicts control of down force through an embodiment of thepresent technology.

FIG. 11 illustrates the down force from the embodiment of FIG. 10.

FIG. 12 is an illustration of a flow control using the presenttechnology.

FIG. 13 is another illustration of the flow control using the presenttechnology.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE TECHNOLOGY

While the present technology is described herein with illustrativeembodiments for particular applications, it should be understood thatthe technology is not limited thereto. Those skilled in the art withaccess to the teachings provided herein will recognize additionalmodifications, applications, and embodiments within the scope thereofand additional fields in which the technology would be of significantutility.

While the technology is described primarily in connection withautomobiles, the disclosure is not limited to automobiles. Thedescriptions below can be applied to other moving objects, such asaircraft, trucks, trailers, and trains, as just a few non-limitingexamples.

The present disclosure describes a plasma actuator that reducesaerodynamic drag resulting from air flow. The reduction of aerodynamicdrag is achieved by creating a plasma region that controls the flowseparation around vehicle body surface. The plasma actuator of thepresent technology is made flush with any surface and is minimallyinvasive to a flow. The plasma actuator in various embodimentsadvantageously has no moving parts, and helps to improve fuel economy byreducing aerodynamic drag, improve vehicle stability control undersevere unsteady flow environments, reduce wind noise around a vehicle,and reduce emission and CO2 foot print through the fuel economyimprovement. By lacking moving parts, the plasma actuator is simpler tomake and generally more robust, not being susceptible to componentfailure at or between movements.

Plasma actuators are used to add energy to low momentum boundary layersand, therefore, delay flow separation. Offsetting the placement of theelectrodes allows the body force to influence the air velocitytangential to the surface. The body force vector can be controlled bythe electrode arrangement and dielectric material. The actuator istypically constructed in an asymmetric configuration with an upper,exposed, electrode and a lower, covered, electrode separated by adielectric material. Plasma actuators are compact, lightweight and offersubstantial control authority by affecting local flow streamlines.Plasma actuators use the high voltage (for example, about 10 kVrms) withfrequency range (for example, about 20 kHz) and demand a low current 0.2A and relatively low power consumption. The plasma actuator responsetime is about a few milliseconds, which is much faster than thehydraulic mechanical actuators (more than 100 second) that are currentlyapplied to performance vehicles.

FIG. 1 is a schematic diagram of a plasma actuator for reducing drag offluid flow—e.g., air flow—according to the present technology. Theplasma actuator has a first electrode 10, generally exposed to air flow16, a second electrode 14 embedded in a dielectric layer 12, and theplasma actuator sits on a substrate 18. The second electrode 14 canextend to a bottom of the dielectric layer 12, and contact the substrate18, as shown in FIG. 1. The substrate 18, and any other part or partsplasma actuator, can be flexible, such as for being shaped to matchdimensions of a target automobile components, as referenced more below.

In various embodiments, a leading edge of the first electrode 10 isspaced (laterally in the view of FIG. 1) from a leading edge of thedielectric layer 12.

In various embodiments, a leading edge of the second electrode 14 isbelow or adjacent a trailing edge (in the direction of the air flow 16)of the first electrode 10, in a direction of the air flow 16 inoperation. The electrodes are in some implementations positioned so thatthey at least partially overlap (in a vertical direction of the view ofFIG. 1, and in others so that they do not overlap at all.

The first electrode 10 and the second electrode 14 are connected to apower source 20 via two separate connectors. While the power source 20can be configured to deliver any of a wide variety of power outputs, invarious embodiments, the power source 20 is capable of delivering 10kVrms. The power source 20 may be a DC or AC source. The plasmaactuators connected to pulsed DC sources are superior in performancethat generate a larger body force at a much lower voltages compared tothe AC plasma actuators. The power consumption of the pulsed DC plasmaactuator with 40 inches long electrode is approximately 1 W which isabout 100 times less than the AC plasma actuators. As the air 16 flowsover the plasma actuator when the first electrode 10 and the secondelectrode 14 are energized by the power source 20, the air flow isionized by the first electrode 10 and the second electrode 14, thuscreating a plasma region 22, as shown in FIG. 2, extending from an edgeof the first electrode 10. In an example, the thickness of theelectrode, measured from the top to the bottom in FIG. 1, is about 0.1mm approximately, the thickness of the dielectric layer, measured fromthe top to the bottom in FIG. 1, varies from about 0.1 mm to about 6 mmdepending on the magnitude of the voltage of the power source. Thedielectric layer is in various embodiments configured with a thicknesssufficient to prevent a short between the two electrodes 10, 14. Thewidth of the electrode, measured from one side to another side in FIG.1, is about 25 mm.

FIG. 2 illustrates another embodiment of the present technology. In FIG.2, the first electrode 10 overlaps the second electrode 14. The twoelectrodes may be separated as shown in FIG. 1 or overlapped as shown inFIG. 2. The second electrode 14 is disposed under the dielectric layer24 and inside the substrate 18 and the plasma region 22 is formed in thedirection of the air flow 16 from a trailing edge of the first electrode10. In various embodiments, a leading edge of the first dielectric 10can align with a front edge of the dielectric layer and/or thesubstrate, as shown in FIG. 2.

FIG. 3 illustrates yet another embodiment of the present technology. Thefirst electrode 10 is disposed above a dielectric layer 24 and exposedto the air flow 16. The second electrode 14 is disposed at leastpartially within a substrate 18. The substrate 18 may be smaller thanthe dielectric layer 24. The first electrode 10 and the second electrode14 are connected to the power source 20. Similar to what has beendescribed for FIGS. 1 and 2, as the air 16 flows over the firstelectrode 10 and the electrodes are energized, the air is ionized andforms a plasma region 22 after of the trailing edge of the firstelectrode 10. The plasma injects energy into the boundary layer of theair flow, thus delaying the flow separation.

As shown, the novel plasma actuator is very effective in reducing dragthough having a relatively simple construction. In various embodiments,the plasma actuator may be configured as a small strip, similar inthickness to a strip of aluminum foil, having or connected to a gluelayer for easy attachment to an automobile body, and then connected to apower source. The thickness of the plasma actuator corresponds to thevoltage of the power source—for instance, the plasma actuator isconfigured to have a thickness based on a known voltage, or the powersource is configured or selected to deliver power having a voltagecorresponding to a pre-determined plasma-actuator thickness. Withrelatively high voltage is required to generate the plasma, the voltagelevel and configuration of the plasma actuator should correspond toavoid damage from excess voltage to the plasma actuator and particularlyits very thin electrodes.

The plasma actuator can be placed on different locations of anautomobile body, preferably at or adjacent (fore or aft of) variousedges around the automobile body where the boundary layer of the airflow tends to separate. FIG. 4 illustrates an automobile body withplasma actuators placed on different surfaces. As a first example, theplasma actuator can be placed on A-pillars 40 to reduce any vortex(reference numeral 82 in FIG. 8 as an example) generally present aroundthe A-pillars 40. The plasma actuator can be positioned, moreparticularly, on or adjacent each A-pillar, such as by being positionedslightly fore or aft of the pillar. The plasma actuator can beconfigured to extend along any of various lengths of the pillar,including along substantially all, or an entirety, of the pillar, asshown in FIG. 4. The plasma actuator is in various embodiments curvedand/or otherwise shaped to match dimensions of the pillar, and/or theplasma actuator comprises materials (some or all) sufficient to renderthe plasma actuator flexible enough to be shaped to (e.g., bend withbend of the pillar) for a flush fit.

A plasma actuator according to the present technology can be used at anyof the vehicle pillars, such as at any one or more of the B-pillars andC-pillars.

A plasma actuator can also be placed around the front fender skirt 42 tocontrol front tire flow separation and to reduce the front tire wake.The plasma actuator can be positioned at or adjacent the skirt, andalong any length thereof. And again, the plasma actuator is in variousembodiments curved and/or otherwise shaped to match dimensions of theskirt, and/or the plasma actuator comprises materials (some or all)sufficient to render the plasma actuator flexible enough to be shaped to(e.g., bend with a bend of the skirt) for a flush fit. The plasmaactuator can be in such cases to be positioned around the correspondingvehicle component—e.g., around the skirt.

A plasma actuator can further be placed at or adjacent the rear fender44 (e.g., a leading edge of the rear fender), and/or a plasma actuatorcan also be positioned at or adjacent the rear fender tail edge 46 tocontrol separation of the rear flow boundary layer and the resultingwake region. Again, the plasma actuator can be positioned at or adjacentthe rear fender or rear-fender tail edge, and along any lengths thereof.And again, the plasma actuator is in various embodiments curved and/orotherwise shaped to match dimensions of the fender or edge, and/or theplasma actuator comprises materials (some or all) sufficient to renderthe plasma actuator flexible enough to be shaped to the render orrear-fender tail edge (e.g., bend with a bend of the rear fender orrear-fender tail edge) for a flush fit. Plasma actuators can be in suchcases to be positioned around the corresponding vehicle component—e.g.,around the rear fender or the rear-fender tail edge.

The plasma actuator can be placed in many other places on the body of anautomobile where air disturbance may be present. For example, FIG. 5illustrates example locations on exposed vehicle surface(s) under thechassis of an automobile where the plasma actuator can be placed. Theplasma actuator can be placed under the front air dam 50, around theunderbody strakes 52, 54, 56. By placing the plasma actuators on theselocations under the chassis, the air disturbance can be reduced andconsequently the drag reduced.

FIG. 6 illustrates locations about a rear of an automobile where theplasma actuators can be placed. The actuators placed around the rearfender tail edge 64 can improve the vehicle aerodynamic stability undera gust or unsteady flow environments. The plasma actuator 60 placed onthe edge of the roof top can also be used to trigger flow separation 66of the air flow flowing around the car body, thus reducing the liftforce and improving the side wind stability. By placing two opposingplasma actuators (FIG. 10) around the rear edge 62 of a trunk, ordecklid, down force 116 can be produced near the end of the vehicle. Therear end down force helps to improve the vehicle stability under severeside wind conditions. The air flow 112 that passes over the two opposingplasma actuators 62 (also FIG. 10) on the edge of the decklid willinteract with the upward flows 114, 110. The interaction between flows112 and 114 will produce down forces 116, 103 as shown in FIGS. 10 and11.

A plasma actuator of the present technology may have differentconstruction that allows a better control of the induced air flow. FIG.10 illustrates an alternative embodiment of a plasma actuator that ismade from connecting two plasma actuators 102 and 104. Each of theplasma actuators 102 and 104 has a construction similar to thatdescribed in FIG. 1. In a contemplated embodiment, one or both plasmaactuators are like that shown in FIG. 2. The plasma actuators 102 and104 are opposed to each other, such as to mirror each other. The plasmaactuators 102 and 104 can be disposed on a common substrate 18 and eachplasma actuator is made from one exposed electrode 10 placed above adielectric layer 12 with another electrode 14 embedded inside thedielectric layer 12 and a power source 20 connecting to both electrodes10 and 14. Each plasma actuator alters the air flow flowing over theplasma actuator. Because two plasma actuators 102, 104 are disposedopposite of each other, the induced flows 106, 108 are opposite of eachother, thus forcing an upward flow 110. This alternative embodiment ofthe plasma actuator, when placed on the edge of the decklid of a car,creates a downward force 103 because of the upward flow 110. Though twoseparate dielectric layers are shown in FIG. 10, they can be replaced byone single dielectric layer covering both plasma actuators 104 and theymay also be powered by one single power source.

The plasma actuator of FIG. 1 can be placed around the front pillar(A-pillar) as shown in FIG. 7. The plasma actuator 70 reduces vortex 78forming at or adjacent the front window 74 and the front windshield 76,thus reducing overall vehicle drag. The plasma actuator can also beplaced around the side mirror 72 to reduce vortex around the sidemirror, and thus overall vehicle drag.

The plasma actuator of the present technology can also be used tocontrol boundary layer flows. FIG. 8 illustrates air 80 flowing in adirection that is generally parallel to lengths of the electrodes 10 and14. As the air 80 flows over the plasma actuator, the plasma actuatorinduces an air flow 16 from the exposed electrode 10 and forms a plasmaregion 22. The induced air flow 16 forms vortex 82 around the plasmaregion 22. The intensity of the induced air flow 16 and the vortex 82depends on a size, or strength, of the plasma region 22, which dependson the intensity of the voltage provided by the power source. The plasmaregion 22 also depends on the distance separating the two electrodes.The boundary layer of a flow can be controlled by positioning the plasmaactuator relative to the air flow. FIG. 12 illustrates positioning theplasma actuator 122 with an induced air 126 flowing against the air 124flowing over the plasma actuator. As the air 124 flows against theinduced air 126, a flow separation region 128 is created. FIG. 13illustrates positioning the plasma actuator 132 in such way that theinduced air 136 flows in generally the same direction as incoming airflow 134.

The plasma actuator alters the characteristics of a fluid flowing over asurface and the plasma actuator of the present technology may be usedfor many different applications. FIG. 9 illustrates placement of aplasma actuator 94 on a wing 90 of an airplane. The plasma actuator 94when activated will induce incoming air flow 16 to flow closer to thesurface of the wing 90 and prevent early, or pre-mature occurrence ofthe flow separation region 92. The plasma actuator may also be placed onthe edge of a propeller of a submarine and alter sonic characteristicsof the submarine.

It is understood that figures are not drawn to scale and relativephysical dimensions between the elements shown in the construction of aplasma actuator may be different from what is shown by differentfigures. It is also understood by those skilled in the art that elementsshown in different figures can be combined to form new embodimentswithin the scope of the present technology.

It is to be appreciated that the Detailed Description section, and notthe Summary and Abstract sections, is intended to be used to interpretthe claims. The Summary and Abstract sections may set forth one or morebut not all exemplary embodiments of the present technology ascontemplated by the inventor(s), and thus, are not intended to limit thepresent technology and the appended claims in any way.

What is claimed is:
 1. A plasma-actuator system, for affectingaerodynamics of a vehicle, comprising: at least one pair of plasmaactuators, the pair of plasma actuators comprising: a left-lateralplasma actuator positioned at a left lateral position of the vehicle to,in operation of the vehicle, affect air flow adjacent the left lateralposition; and a right-lateral plasma actuator positioned at a rightlateral position of the vehicle to, in operation of the vehicle, affectair flow adjacent the right lateral position; wherein each of the plasmaactuators comprises two electrodes.
 2. The plasma-actuator system ofclaim 1 wherein: the left lateral position is at or adjacent a leadingedge of a left rear fender of the vehicle, and the left-lateral plasmaactuator, in operation of the vehicle, affects air flow adjacent theleading edge of the left rear fender; and the right lateral position isat or adjacent a leading edge of a right rear fender of the vehicle, andthe right-lateral plasma actuator, in operation of the vehicle, affectsair flow adjacent the leading edge of the right rear fender.
 3. Theplasma-actuator system of claim 1 wherein: the left lateral position isat a left third-from-the-front, C, pillar of the vehicle and theleft-lateral plasma actuator, in operation of the vehicle, affects airflow adjacent the left second, B, pillar of the vehicle; and the rightlateral position is at a right third-from-the-front, C, pillar of thevehicle and the right-lateral plasma actuator, in operation of thevehicle, affects air flow adjacent the right third, C, pillar of thevehicle.
 4. The plasma-actuator system of claim 1 wherein: the leftlateral position is at a left second-from-the-front, B, pillar of thevehicle and the left-lateral plasma actuator, in operation of thevehicle, affects air flow adjacent the left second, B, pillar of thevehicle; and the right lateral position is at a rightsecond-from-the-front, B, pillar of the vehicle and the right-lateralplasma actuator, in operation of the vehicle, affects air flow adjacentthe right second, B, pillar of the vehicle.
 5. The plasma-actuatorsystem of claim 1 wherein: the left lateral position is at a left first,A, pillar of the vehicle and the left-lateral plasma actuator, inoperation of the vehicle, affects air flow adjacent the left first, A,pillar of the vehicle; and the right lateral position is at a rightfirst, A, pillar of the vehicle and the right-lateral plasma actuator,in operation of the vehicle, affects air flow adjacent the right first,A, pillar of the vehicle.
 6. The plasma-actuator system of claim 1wherein: the left lateral position surrounds a left vehicle mirror atleast partially and the left-lateral plasma actuator, in operation ofthe vehicle, affects air flow adjacent the left vehicle mirror; and theright lateral position surrounds a right vehicle mirror at leastpartially and the right-lateral plasma actuator, in operation of thevehicle, affects air flow adjacent the right vehicle mirror.
 7. Theplasma-actuator system of claim 1 wherein: the left lateral position isat a trailing edge of a left rear fender of the vehicle, and theleft-lateral plasma actuator, in operation of the vehicle, affects airflow adjacent the trailing edge of the left rear fender; and the rightlateral position is at a trailing edge of a right rear fender of thevehicle, and the right-lateral plasma actuator, in operation of thevehicle, affects air flow adjacent the trailing edge of the right rearfender.
 8. The plasma-actuator system of claim 1 wherein: the leftlateral position is at a left-side aft end of the vehicle, and theleft-lateral plasma actuator, in operation of the vehicle, affects airflow adjacent the left-side aft end; and the right lateral position isat a right-side aft end of the vehicle, and the right-lateral plasmaactuator, in operation of the vehicle, affects air flow adjacent theright-side aft end.
 9. The plasma-actuator system of claim 1 wherein:the left lateral position is at a trailing edge of a left front fenderof the vehicle, and the left-lateral plasma actuator, in operation ofthe vehicle, affects air flow adjacent the trailing edge of the leftfront fender; and the right lateral position is at a trailing edge of aright front fender of the vehicle, and the right-lateral plasmaactuator, in operation of the vehicle, affects air flow adjacent thetrailing edge of the right front fender.
 10. The plasma-actuator systemof claim 1 wherein: the left lateral position is at a leading edge of aleft front fender of the vehicle, and the left-lateral plasma actuator,in operation of the vehicle, affects air flow adjacent the leading edgeof the left front fender; and the right lateral position is at a leadingedge of a right front fender of the vehicle, and the right-lateralplasma actuator, in operation of the vehicle, affects air flow adjacentthe leading edge of the right front fender.
 11. The plasma-actuatorsystem of claim 1 wherein: the left lateral position is at a left-sidefront end of the vehicle, and the left-lateral plasma actuator, inoperation of the vehicle, affects air flow adjacent the left-side frontend; and the right lateral position is at a right-side front end of thevehicle, and the right-lateral plasma actuator, in operation of thevehicle, affects air flow adjacent the right-side front end.
 12. Theplasma-actuator system of claim 1 wherein: the left lateral position isat a left side of a vehicle decklid, and the left-lateral plasmaactuator, in operation of the vehicle, affects air flow adjacent theleft side of the vehicle decklid; and the right lateral position is at aright side of the vehicle decklid, and the right-lateral plasmaactuator, in operation of the vehicle, affects air flow adjacent theright side of the vehicle decklid.
 13. The plasma-actuator system ofclaim 1 wherein each of the plasma actuators has, in at least a portionof the actuator, one or both of an elongate shape and a curved shape.14. The plasma-actuator system of claim 1 wherein each plasma actuator,in affecting air, reduces aerodynamic drag on the vehicle by reducingdisturbance of air flowing passing by the vehicle.
 15. A plasma-actuatorsystem, for affecting aerodynamics of a vehicle, comprising: a centrallydisposed plasma actuator; wherein the centrally disposed plasma actuatoris, for use of the system, positioned at a laterally central position,along a centerline of the vehicle; and wherein the centrally disposedplasma actuator, in operation of the vehicle, affects air flow adjacentthe central position.
 16. The plasma-actuator system of claim 15,wherein the central position is at an aft end of a roof of the vehicle.17. The plasma-actuator system of claim 15, wherein the central positionis at or adjacent a decklid of the vehicle.
 18. The plasma-actuatorsystem of claim 15, wherein the central position is at or adjacent ahood of the vehicle.
 19. The plasma-actuator system of claim 15, whereineach of the plasma actuators has, in at least a portion of the actuator,one or both of an elongate shape and a curved shape.
 20. Aplasma-actuator system, for affecting aerodynamics of a vehicle,comprising: at least one plasma-actuator arrangement selected from agroup consisting of: at least one pair of plasma actuators comprising: aleft-lateral plasma actuator positioned at a left lateral position ofthe vehicle to, in operation of the vehicle, affect air flow adjacentthe left lateral position; and a right-lateral plasma actuatorpositioned at a right lateral position of the vehicle to, in operationof the vehicle, affect air flow adjacent the right lateral position; anda centrally disposed plasma actuator, wherein: the centrally disposedplasma actuator is, for use of the system, positioned at a laterallycentral position, along a centerline of the vehicle; and the centrallydisposed plasma actuator, in operation of the vehicle, affects air flowadjacent the central position; wherein each of the plasma actuatorscomprises two electrodes.